Apply OwnPtr|PassOwnPtr to m_validationMessageClient and setValidationMessageClient() in Page class

Source/core/page/Page.h

Index: Source/core/page/Page.h
diff --git a/Source/core/page/Page.h b/Source/core/page/Page.h
index 7248f896cdda0553437183aaccddba16f8fc5dfa..41869d9103be4c39fcd12c1706d8c42dc7f46277 100644
--- a/Source/core/page/Page.h
+++ b/Source/core/page/Page.h
@@ -151,8 +151,8 @@ public:
     ContextMenuController& contextMenuController() const { return *m_contextMenuController; }
     InspectorController& inspectorController() const { return *m_inspectorController; }
     PointerLockController& pointerLockController() const { return *m_pointerLockController; }
-    ValidationMessageClient* validationMessageClient() const { return m_validationMessageClient; }
-    void setValidationMessageClient(ValidationMessageClient* client) { m_validationMessageClient = client; }
+    ValidationMessageClient& validationMessageClient() const { return *m_validationMessageClient; }
+    void setValidationMessageClient(PassOwnPtr<ValidationMessageClient>);
 
     ScrollingCoordinator* scrollingCoordinator();
 
@@ -258,9 +258,9 @@ private:
 
     BackForwardClient* m_backForwardClient;
     EditorClient* const m_editorClient;
-    ValidationMessageClient* m_validationMessageClient;
     SpellCheckerClient* const m_spellCheckerClient;
     StorageClient* m_storageClient;
+    OwnPtr<ValidationMessageClient> m_validationMessageClient;
 
     UseCounter m_useCounter;